94 THEORY OF EVOLUTION 



state that we call an animal or plant come from 

 the fertilized egg. An hour or two after fer- 

 tilization the egg divides into two cells (fig. 

 47). Then each half divides again. Each 



FIG. 47. An egg, and the division of the egg the so-called 

 process of cleavage. (After Selenka.) 



